"The kid starts cackling, and I realise he invented his own question in order to trick me into saying it," the teacher wrote.

Singapore’s mind-bending logical riddles are so last month. Enter: Vietnam, the latest country to be swept up in what could easily be known as “the viral-math epidemic of 2015.” This one might even ...

A tricky math question on a second grader's assignment left one mother puzzled. In fact, she was so stumped by the word problem that she turned to the internet for help. Angie Werner called on fellow ...